The BBC reviews the Raspberry Pi. "The device may inspire a new generation of computer programmers or it could leave children used to smartphones and tablet computers baffled and bewildered. A great experiment with the way we teach computing has begun and we can't be sure how it will end." Mine's coming the week of May 21.

Most of the older computers may have been instant on (plus monitor warm up), but in truth they weren't typically usable if you had a disk drive unless it booted from the drive. The cassette typically came in built to the ROM and worked fine, but the DOS had to load.

That said, all of my current Macs are EFFECTIVELY instant on. Yes, my desktops are basically in low power sleep, but my iPhone and laptops are in more of a catatonic sleep. I don't know when the last time my mac laptop was actually rebooted.

I don't know the power and sleep support that RPi has. And, out of the box, it doesn't have a spot for a battery to maintain state and live unplugged.

But, I think it is likely effectively "instant on" for most use cases. It won't be instant on when you take it from home to school or whatever, but c'est la vie. Someone can come up with a battery backed up case. I wonder how long the thing will stay alive in sleep mode on 4 AA batteries, or some commodity cell phone battery that costs more than the computer.

My experience with home computers in the 80's was limited to the Commodore 64 and 128. Both could access the disk drive without the need of any extra software, although the C64's way of using the disk drive was a bit awkward.

I think the main advantage, from an educational point, was that home computers didn't change. Windows/Linux/OSX computers get operating system updates, they come on changing hardware, you can customize the way everything looks.

A home computer always comes on with the same screen, its build-in programming language stays the same, the chips don't change. It gave you a chance to really get to know the computer and figure out how it works. There weren't so many layers between you and the computer like there are now.

I really like my Macs, but I can't love them like I did my Commodore 64.